Just the Headband and the transparent shield. That is all that is needed to create a fully functional face shield. This will allow the parts to be produced and assembled more quickly and at a larger scale.
If you would like to secure the mask through more than "spring action" then velcro can easily be adhered to the 3D Printed straps to cinch it down firmly.
This updated design is compatible with the Prusa FaceShield parts as well.
If you would like to 3D Print and assemble this face mask yourself for your local community feel free. Please be sure to exercise precautions such as a mask and glove to ensure that you do not contaminate healthcare personnel.